It is widely known to use geothermal steam obtained from geothermal wells to generate electrical power in geothermal power plants. One problem heretofore extant with the production of geothermal power has been the abatement or removal of hydrogen sulfide from geothermal steam before the discharge thereof to the environment. Various technology is in place for the abatement of hydrogen sulfide during the drilling of geothermal wells, and also in the treatment of steam condensate from the turbine through which the geothermal steam is expanded to generate electrical power. Exemplary of such technology are U.S. Pat. Nos. 4,696,802; 4,629,608; and 4,468,929. Even efforts by geothermal steam suppliers to prevent the discharge of the geothermal steam from geothermal steam gathering systems that supply geothermal power plants have been reasonably successful in spite of the size and complexity of the systems typically employed.
However, one major difficulty persists, that of disposing of geothermal steam during geothermal power plant outages. The usual action taken on shutdown of a power plant is to vent steam at a reduced flow through a noise silencer or muffler to the atmosphere. This procedure is commonly referred to in the industry as "steam stacking", and this term is used inclusively of venting of steam during power plant shutdowns or outages, either scheduled or unscheduled.
Steam stacking is generally less than satisfactory from both environmental and resource conservation points of view. The steam supplier does not ordinarily incorporate process equipment for removing H.sub.2 S from steam supplied to the power plant. Thus, when steam is stacked by the supplier, hydrogen sulfide is released unabated to the atmosphere. To ensure that hydrogen sulfide emissions do not exceed regulated levels, measures are necessary either to remove the hydrogen sulfide from the stacked steam or to handle the steam in such a way that it will not be vented to the atmosphere. It has been suggested to remove hydrogen sulfide from the steam before it enters the geothermal plant. Another possibility includes diverting the steam around the power plant turbine, i.e. a turbine bypass, to the condenser and the downstream hydrogen sulfide abatement equipment, e.g. Stretford and/or hydrogen peroxide-supplemented catalyst processes. It has further been suggested to reroute the steam to another power plant or to construct dual, parallel geothermal plants supplied with steam from a single steam gathering system. All of these strategies have inherent limitations and disadvantages.